*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    :root {
      --bg: #0f0f0f;
      --surface: #1a1a1a;
      --surface2: #242424;
      --border: #333333;
      --text: #f5f5f5;
      --text2: #999999;
      --blue: #ff6b00;
      --green: #ff8c33;
      --accent: #ff7a1a;
    }
    body {
      background: var(--bg);
      color: var(--text);
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      min-height: 100vh;
      padding: 24px 16px;
    }
    header { text-align: center; margin-bottom: 32px; }
    header h1 {
      font-size: 2rem;
      font-weight: 700;
      background: linear-gradient(135deg, #ff6b00, #ff9f40);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      margin-bottom: 8px;
    }
    header p { color: var(--text2); font-size: 0.95rem; }
    .container { max-width: 1100px; margin: 0 auto; }
    #drop-zone {
      border: 2px dashed var(--border);
      border-radius: 12px;
      padding: 48px 24px;
      text-align: center;
      cursor: pointer;
      transition: border-color 0.2s, background 0.2s;
      margin-bottom: 32px;
      background: var(--surface);
    }
    #drop-zone:hover, #drop-zone.drag-over {
      border-color: var(--blue);
      background: var(--surface2);
    }
    #drop-zone .icon { font-size: 3rem; margin-bottom: 12px; display: block; }
    #drop-zone p { color: var(--text2); margin-bottom: 8px; }
    #drop-zone label { color: var(--blue); cursor: pointer; text-decoration: underline; }
    #file-name { color: var(--accent); font-size: 0.9rem; margin-top: 8px; }
    #error-msg { color: #f87171; font-size: 0.9rem; margin-top: 8px; }
    #loading-msg { color: var(--text2); font-size: 0.9rem; margin-top: 8px; }
    #metrics-section { margin-bottom: 32px; }
    #metrics-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 16px;
    }
    @media (max-width: 768px) { #metrics-grid { grid-template-columns: repeat(2, 1fr); } }
    .metric-card {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 12px;
      padding: 20px;
      text-align: center;
    }
    .metric-label {
      color: var(--text2);
      font-size: 0.8rem;
      text-transform: uppercase;
      letter-spacing: 0.05em;
      margin-bottom: 8px;
    }
    .metric-value { font-size: 2rem; font-weight: 700; color: var(--accent); line-height: 1; }
    .metric-value .unit { font-size: 1rem; color: var(--text2); font-weight: 400; margin-left: 4px; }
    #charts-section { margin-bottom: 32px; }
    .chart-wrapper {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 12px;
      padding: 20px;
      margin-bottom: 16px;
    }
    .chart-wrapper h2 { font-size: 1rem; color: var(--text2); margin-bottom: 16px; font-weight: 500; }
    .chart-container { position: relative; height: 280px; }
    #config-section {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: 12px;
      overflow: hidden;
    }
    #config-section details { border-bottom: 1px solid var(--border); }
    #config-section details:last-of-type { border-bottom: none; }
    #config-section summary {
      padding: 16px 20px;
      cursor: pointer;
      font-weight: 500;
      color: var(--text2);
      user-select: none;
    }
    #config-section summary:hover { color: var(--text); }
    .config-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
      gap: 12px;
      padding: 0 20px 20px;
    }
    .config-grid label { display: flex; flex-direction: column; gap: 6px; color: var(--text2); font-size: 0.85rem; }
    .config-grid input, .config-grid select {
      background: var(--bg);
      border: 1px solid var(--border);
      border-radius: 6px;
      color: var(--text);
      padding: 8px 10px;
      font-size: 0.9rem;
      width: 100%;
    }
    .config-grid input:focus, .config-grid select:focus { outline: none; border-color: var(--blue); }
    .config-actions { padding: 16px 20px; border-top: 1px solid var(--border); }
    #btn-recalculate {
      background: var(--blue);
      color: white;
      border: none;
      border-radius: 8px;
      padding: 10px 24px;
      font-size: 0.95rem;
      cursor: pointer;
      font-weight: 500;
      transition: opacity 0.2s;
    }
    #btn-recalculate:disabled { opacity: 0.4; cursor: not-allowed; }
    #btn-recalculate:not(:disabled):hover { opacity: 0.85; }